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Commit 5b11abfd authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt
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powerpc/pci: mmap anonymous memory when legacy_mem doesn't exist 



The new legacy_mem file in sysfs is causing problems with X on machines
that don't support legacy memory access. The way I initially implemented
it, we would fail with -ENXIO when trying to mmap it, thus exposing to
X that we do support the API but there is no legacy memory.

Unfortunately, X poor error handling is causing it to fail to start when
it gets this error.

This implements a workaround hack that instead maps anonymous memory
instead (using shmem if VM_SHARED is set, just like /dev/zero does).

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent d87bf766

arch/powerpc/kernel/pci-common.c

+15 −2
Original line number Diff line number Diff line
@@ -561,8 +561,21 @@ int pci_mmap_legacy_page_range(struct pci_bus *bus, 
		 (unsigned long long)(offset + size - 1));



	if (mmap_state == pci_mmap_mem) {

		if ((offset + size) > hose->isa_mem_size)

			return -ENXIO;

		/* Hack alert !

		 *

		 * Because X is lame and can fail starting if it gets an error trying

		 * to mmap legacy_mem (instead of just moving on without legacy memory

		 * access) we fake it here by giving it anonymous memory, effectively

		 * behaving just like /dev/zero

		 */

		if ((offset + size) > hose->isa_mem_size) {

			printk(KERN_DEBUG

			       "Process %s (pid:%d) mapped non-existing PCI legacy memory for 0%04x:%02x\n",

			       current->comm, current->pid, pci_domain_nr(bus), bus->number);

			if (vma->vm_flags & VM_SHARED)

				return shmem_zero_setup(vma);

			return 0;

		}

		offset += hose->isa_mem_phys;

	} else {

		unsigned long io_offset = (unsigned long)hose->io_base_virt - _IO_BASE;